An important concept to note regarding channel assignments is that the channel actually represents the center frequency that the transceiver within the radio and access point uses (e.g., 2.412 GHz for channel 1 and 2.417 GHz for channel 2). There is only 5 MHz separation between the center frequencies, and an 802.11b signal occupies approximately 30 MHz of the frequency spectrum. The signal falls within about 15 MHz of each side of the center frequency. As a result, an 802.11b signal overlaps with several adjacent channel frequencies. This leaves you with only three channels (channels 1, 6, and 11 for the U.S.) that you can use without causing interference between access points.
Thanks for the reply. One of the books I am refering to is actually the first link you posted :-)
I guess my main confusion is :-
If the signal is spread over a range of frequencies, then when is the "phase shift"
Does the reciever first mix all the recieved signals in the frequency range to form a single waveform and THEN analyse / intreperet the waveform for phase shifts ?
i.e Is the flow something like :-
Signal is DBPSK modulated --> Resulting sine wave is spread across frequency range ---> Rx then joins all the frequencies back to produce a single sinewave ---> Phase shift in resulting sine wave is converted to binary 1/0